The invention relates to an immersed casting tube for introducing a metal melt, in particular a steel melt, into a continuous casting mold having wide side walls and narrow side or end walls and forming a strand with wide sides and narrow sides, in particular a thin-slab continuous casting mold, wherein the immersed casting tube comprises a tube section provided with lateral openings for the metal melt whose central axes are substantially oriented towards the narrow sides of the strand, and a bottom portion provided with a bottom opening for the metal melt.
High casting rates call for a high ejection speed of the casting jets emerging from the immersed casting tube. When using presently known immersed casting tubes, only a poor to medium product quality, i.e., quality of the strand, can thus be obtained. Due to melt flowing out of the immersed casting tube in the lateral directions, the meniscus of the melt is rather disturbed and uneven. On account of a downwardly directed melt flow, the melt can penetrate deeply into the interior of the strand. Not only will a partial remelting of the already solidified strand skin occur due to the newly arriving hot melt, but also the casting powder applied on the meniscus and impurities depositing on the meniscus will be entrained and flushed into the interior of the strand. If the melt emerging from the immersed casting tube primarily flows downwards, only a poor melting rate of the casting powder can be obtain, and the friction between the casting powder and the mold side walls will become undesiredly high.
Therefore, attempts have been made to positively influence the flow conditions within a strand by shaping casting tubes in a particular manner, and immersed casting tubes, which have both lateral openings and bottom openings, have been produced. Such immersed casting tubes of the initially defined kind are known, for instance, from AT-B-332,579; JP-A-58-47545 and AT-B-331,428. However, the above-described drawbacks could not be avoided with these known immersed casting tubes. In particular, it has not been possible to obtain acceptable qualities when casting thin slabs at high casting rates.
From WO89/12519 an immersed casting tube is known, in which two crossing or intersecting casting jets emerge from the bottom region or from the lateral region of the immersed casting tube. According to a further embodiment, casting jets cross or intersect each other in the interior of the immersed casting tube before emerging laterally. Also with these known immersed casting tubes, it is not feasible to meet the diverging demands of a high casting rate and a slight yet sufficient movement of the bath on the meniscus as well as a slight vertical depth of penetration of the casting jet into the liquid core of the strand.